It looks like a new "locally integrated menu" will make it into Unity, starting with version 5.6.0. There's basically no information about the new locally integrated menubar, except for two bug reports which link to some custom Unity, Compiz, Metacity and Light Themes branches so to see "LIM" in action, I've compiled all these branches and here's the result. The "locally integrated menubar" can be displayed on the panel (for maximized windows) as well as in the window decoration (unmaximized windows). But it's not displayed on both in the same time.

This is awful. First they throw away local menu bars, which are and were always a Good Idea (but Apple doesn't have them so let's do what they do first and ask questions later) then they break stuff even more by bringing them back, except remarkably more terrible (no key accelerators or menu titles visible at a glance, extra mouse click on an obscure-looking icon required to even enter the menu of menus...)

Why? Does anyone really need to save ~12px of vertical space when almost everyone has 900+ vertical pixels of resolution?

Is it so bad that stuff's looked the same since 1995 that we have to go around destroying functional, effective paradigms and interfaces just to be different and pretend we're innovating?

No one ever asked for this. People put up with Apple's and Microsoft's "let's-break-our-UI-again" crap because they more or less have to, but no one has to use Ubuntu.